Liquid crystal display device

ABSTRACT

In a case where a frame display is provided on a display screen of a liquid crystal panel, the prior art necessitates data for frame display to be directly written to all the display data or 2 screenful of data to be prepared and overwritten on each other. To overcome this problem, a liquid crystal display device of the invention has an arrangement wherein a segment electrode and a common electrode constituting a pixel to be driven for normal image display are applied with a driving waveform from a driver IC, and wherein a common electrode to be placed in a normally ON state is applied with a waveform exceeding a selection voltage of any segment signal waveform for liquid crystal selection while a segment electrode to be placed in a normally ON state is applied with a waveform exceeding a selection voltage of any common signal for liquid crystal selection. This permits a frame to be displayed on the display screen.

BACKGROUND-OF THE INVENTION

The present invention relates to a driving device for liquid crystaldisplay panel of a passive drive system and to a liquid crystal displaydevice and an electronic device employing the same.

A passive-drive liquid crystal display panel widely used in electronicdevices has a structure wherein a liquid crystal layer is sealed betweena transparent plate formed with a plurality of line-shaped commonelectrodes and a transparent counter plate formed with a plurality ofline-shaped segment electrodes. Individual intersections of the commonelectrodes and the segment electrodes define individual pixels whichconstitute a display screen. That is, the display screen of m×n pixelsis essentially composed of m segment electrodes and n common electrodes.ON/OFF control of each pixel is accomplished by way of a signal (drivingsignal waveform) applied to the segment electrode and the commonelectrode. Such a liquid crystal display device has a problem that anobserver cannot instantaneously determine whether a pixel is OFF becauseit is located outside a display screen or because an OFF signal isinputted thereto. In other words, a boundary between the display screenand a non-display area is unrecognizable for the observer unless anoutermost portion of the display screen (displayable area) isilluminated. For example, a commonly used color liquid crystal panel isblack in an OFF state (with no voltage applied). Therefore, when a photoor game graphic with a black background is displayed on such a panel,the outermost portion of the display screen (display area) isunrecognizable. This may lead to a demand for a so-called frame displaywherein outermost edges of the display screen are constantlyilluminated. On the other hand, the current cellular phones or portableinformation terminals are generally limited in the number of displaypixels in order to expedite the display of information provided vianetwork services or by add-on applications. As to the portableinformation terminal, for instance, the number of display pixels dependsupon an OS used therein. Normally, the OS does not give considerationsto the frame display. Hence, the following method is commonly used toprovide the frame display outside the display screen of m×n pixels basedon the conventional passive-drive system. That is, additional pixels forframe display are provided outside the display screen so that(m+2)×(n+2) pixels in total are arranged. A graph-plotting capability isused to draw a frame while a primary display image is written to awindow (display screen of m×n pixels) inside the frame. Specifically,SSD1780, a conventional liquid crystal driver commercially availablefrom SOLOMON Systech Limited is capable of writing frame data on arespective line on vertically and laterally opposite sides externally ofthe display screen by utilizing a 2D graph-plotting capability of adisplay controller, which is called 2D graphic Limitation GraphicAcceleration (refer to, for example, non-patent document 1). However,commonly used liquid crystal drivers and controllers are not equippedwith such a capability so that liquid crystal panels adapted for theframe display based on this method are limited. In addition, there isanother problem that the IC having such a capability is more expensivethan the common ICs. [Non-patent Document 1] The specification of theliquid crystal driver SSD1780 commercially available from SOLOMONSystech Limited (SSD1780-0.15 Full Version Specification, P42, Item93.1-93.6) retrieved on Sep. 26, 2002 via internet service (URLhttp://www.solomon-systech.com/products/product_lists.htm).

As described above, the attempt to provide the frame display outside thedisplay screen can be accomplished only when the specific controller ordriver is used. This imposes restriction on the specification of theliquid crystal display device. In addition, a significant cost must beborne in order to utilize the IC having such a capability.

In view of the foregoing, it is an object of the invention to permit anycontroller or driver to provide the frame display outside the displayscreen in an easy and less-costly manner without increasing the scale ofthe driving circuit.

SUMMARY OF THE INVENTION

According to the invention directed to the solution to the aboveproblems, a liquid crystal display device has an arrangement whereindummy segment electrodes and dummy common electrodes are disposed atmarginal. areas around a display screen including a group of segmentelectrodes and a group of common electrodes, and wherein the dummysegment electrodes are applied with a segment signal waveform exceedinga selection voltage of any common signal for liquid crystal selectionand the dummy common electrodes are applied with a common signalwaveform exceeding a selection voltage. of any segment signal waveformfor liquid crystal selection, whereby a frame is displayed outside thedisplay screen.

In another aspect, the dummy electrodes are applied with a waveformwhich is synthesized with a driving waveform applied to the segment.electrode group to provide a synthesized waveform having an effectivevalue higher than an effective value of a waveform applied to aturned-ON liquid crystal in the display screen.

It is noted here that the waveform applied to the dummy segmentelectrodes or the dummy common electrodes. is not formed based on. asignal outputted from the driver IC just as in the conventional imagedisplay process, but is rather formed based on a signal inputted to thedriver IC.

The waveform applied to the dummy common electrodes is asynchronous toan FLM signal, has an equal HL time in one period, and does not coincidewith an M signal.

As a specific example of the waveform applied to the dummy commonelectrodes, there may be used a signal waveform obtained by dividingdown the M signal for level shift to the same potential as that of asegment voltage.

As another example of the above waveform, there may be used a signalwaveform obtained by dividing down the M signal to ½.

In another aspect of the invention, the waveform applied to the dummysegment electrodes is defined to be a signal waveform having the sameperiod as the M signal and the same potential as the waveform applied tothe dummy common electrodes.

In this manner, the waveforms applied to the segment electrodes andcommon electrodes responsible for the frame display can be formed basedon the input signal to the driver IC. This permits any type ofcontroller or driver to provide the frame display outside the displayscreen in an easy and less-costly manner without increasing the scale ofthe driving circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing a wiring pattern of a displayscreen of a liquid crystal display panel used in a liquid crystaldisplay device of the invention;

FIG. 2 is a chart showing specific examples of signal waveforms used inthe liquid crystal display device of the invention; and

FIG. 3 is a block diagram showing an example of circuits for generatinga waveform of a dummy segment signal or of dummy common signal-accordingto the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A liquid crystal display device according to the invention includes aliquid crystal panel, and a driver IC for driving the liquid crystalpanel wherein a liquid crystal layer is interposed between a transparentplate provided with a group of segment electrodes and a transparentcounter plate provided with a group of common electrodes. The driver ICapplies a respective signal (driving signal waveform) to a segmentelectrode and a common electrode constituting a pixel to be driven fornormal image display, whereas the IC driver applies a frame-displaycommon signal and a frame-display segment signal to a common electrodeand a segment electrode to be driven for frame display, respectively.Specifically, the frame-display common signal has such a waveform as toexceed a selection voltage of any segment signal. waveform for liquidcrystal selection, whereas the frame-display segment signal has such awaveform as to exceed a selection voltage of any common signal forliquid crystal selection. Thus is accomplished a frame display on adisplay screen (lines in a normally-ON state are present).

A segment electrode (line) to be placed in the ON state is applied withthe same waveform as that representative of segment selection data(All-ON data) used in a normal display drive. A common waveform fornormal display drive is applied to a group of common electrodesintersecting with the segment electrode and hence, all the pixelsconstituted by the segment electrode are applied with a voltage of aneffective value equivalent to white display data. Thus is displayed avertical frame line on the screen.

A common electrode (line) to be placed in the ON state is applied withsuch a frame-display common waveform as to permit the application of avoltage exceeding the voltage for liquid crystal selection irrespectiveof display data (waveform) applied to segment electrodes intersectingwith the. common electrode. Thus, all the pixels constituted by thecommon electrode are applied with a voltage higher than an effectivevalue for liquid crystal display so that a horizontal frame line isdisplayed on the screen. The frame-display common waveform may be anyone that is asynchronous to an FLM signal, has an equal HL time in oneperiod, and does not coincide with an M signal. The frame-display commonwaveform is defined as the above for the following reason. Where awaveform synchronous to the FLM signal or coinciding with the M signalis used as the frame-display common signal, an image displayed based onsegment display data will detrimentally appear to be a common electrodeto be placed in the normally-ON state. A usable frame-display commonwaveform maybe exemplified by a signal waveform which is obtained bydividing down the M signal for level shift to the same potential as thatof a segment voltage.

On the other hand, a waveform applied to a segment electrode to beplaced in the ON state may have the same period as the M signal and thesame potential as the waveform applied to a common electrode to beplaced in the ON state.

In this manner, the waveform applied to the common electrode or thesegment electrode to be placed in the normally-ON state can be generatedbased on the input signal to the driver IC and the potential for drivingthe liquid crystal panel. Therefore, the object of the invention can beachieved by merely adding a simple circuit without increasing the scaleof the liquid crystal driver circuit.

Embodiment

FIG. 1 schematically shows a construction of a display screen (wiringpattern) of a liquid crystal display device according to an embodimentof the invention. As shown in FIG. 1, a display screen 2 of a liquidcrystal panel is essentially composed of m×n pixels. In a screenportion, m segment electrode wirings formed on a transparent plate and ncommon electrode wirings formed on a transparent counter plate intersectwith one another to define the pixels. The segment electrode wirings andthe common electrode wirings are applied with a liquid crystal controlsignal (driving signal) for image display from unillustrated segmentdriver IC and common driver IC, respectively. Dummy segment wirings 4, 5are laid on laterally opposite sides externally of the aforesaid m×npixels (display screen 2). Dummy common wirings 1, 3 are also laid onvertically opposite sides externally of the m×n pixels. The dummysegment wirings 4, 5 are applied with a signal waveform exceeding aselection voltage of any common signal for liquid crystal selection,whereas the dummy common wirings 1, 3 are applied with a common signalwaveform exceeding a selection voltage of any segment signal waveformfor liquid crystal selection. Thus is effected the display of a frameoutside the display screen. The common signal (dummy common signal)applied to the dummy common wirings has a waveform which is asynchronousto an FLM signal, has an equal HL time in one period, and does notcoincide with an M signal. For example, a usable dummy common signal mayhave a signal waveform obtained by dividing down the M signal for levelshift to the same potential as that of a segment voltage. In thismanner, the dummy common signal may be generated based on the inputsignal to the driver IC and the potential for driving the liquid crystalpanel. Thus, the frame display can be accomplished by merely adding asimple circuit without increasing the scale of the liquid crystal drivercircuit.

Next, how the liquid crystal panel of the embodiment is driven will bedescribed with reference to FIG. 2. FIG. 2 shows exemplary waveforms ofdriving waveforms applicable to the embodiment of the invention. Anormal display screen displays an image based on a signal supplied tothe segment electrodes and a signal supplied to the common electrodes.The figure illustrates waveforms of a segment signal SEG1 and of acommon signal COM1 as typical examples of the driving signals. A drivingmethod using such signals is known as the APT driving scheme (Alt &Pleshko Technique, Scanning Limitation Liquid Crystal Displays, IEEETrans Electronic DEV ED-21.146-155 (1974)). The waveforms shown in FIG.2 are used for driving a liquid crystal panel including a display screenof 160 pixels (segment lines: 16, common lines: 10) at a Duty of 1/10and a bias of 1/12. In this case, display data providing a checkeredpattern display on the screen are applied to the segment electrodes andcommon electrodes. The other driving conditions are set as follows:V0=3.0V, VM=1.5V, V1=GND, VH=18V, VL=−15V. It is noted here that the FLMsignal is indicative of a period of the display screen. The M signal isfor generating. an AC field in the liquid crystal or for driving toensure that no DC component remains in the liquid crystal panel. Asshown in FIG. 2, the embodiment uses, as the M signal, a signal obtainedby dividing down an LP signal to ⅓. The FLM signal, LP signal and Msignal described here are inputted to the segment driver IC or thecommon driver IC.

Next, the dummy segment signal is for driving the dummy segment wirings4, 5. The COM1 represents an example of a waveform inputted to thecommon electrode wirings responsible for image display. That is, theCOM1 is an example of the waveform outputted from the common driver IC.White frame portions on the laterally opposite sides of the displayscreen (dummy segment wiring areas) provide display based on the sameprinciples as those of the typical APT driving scheme. These areas areapplied with the M signal, a voltage amplitude of which is adjusted forlevel shift to the same potential as that of a segment voltage VOapplied in the APT drive. That is, the same waveform as a drivingwaveform applied in the APT drive for turning ON all the pixels of acertain segment (switching to white display) is generated in a separatecircuit and applied to the dummy segments. This waveform is synthesizedwith a common waveform applied in the APT drive such that a voltage ofan effective value equivalent to ON display data may be applied to dotsdefined at intersections of the dummy segment wirings. As a result, theportions of the dummy segment wirings can be constantly placed in the ONdisplay state irrespective of the driving waveform applied to the commonside in the APT drive.

Next, the dummy common signal is for driving the dummy common wirings 1,3. The SEG1 represents an example of a waveform inputted to the segmentelectrode wirings responsible for image display, or an example of thewaveform outputted from a segment driver circuit IC6. A synthesizedwaveform is synthesized from the SEG1 and a dummy common signal. It isnoted here that the dummy common signal is obtained by dividing down theliquid-crystal AC-field generating signal (M signal) to ½ for levelshift to the same potential as the segment voltage V0 for the APT drive,thus ensuring that a voltage exceeding the selection voltage for liquidcrystal is applied to the dummy common wirings irrespective of thedisplay data. The segment electrode wirings intersecting with the dummycommon wirings are applied with the waveform for APT drive while all thepixels constituted by the dummy common wirings are applied with avoltage exceeding the effective value for liquid crystal. Therefore, allthe pixels constituted by the dummy common wirings are placed in the ONdisplay state. In this manner, ON display lines are displayed onvertically opposite sides of the display screen.

Specific description is made on how display is effected based on thesewaveforms. The data indicative of the checkered pattern display assumethe waveform such as of the SEG1 during the APT drive. The dummy commonwirings are applied with the dummy common waveform obtained by dividingdown the M signal to ½ for level shift to the potential of the segmentdriving waveform. The white-frame display portions on the verticallyopposite sides of the display screen are applied with the waveformsynthesized from these two waveforms. An effective value of thesynthesized waveform may be calculated using the following equation 1:${Vrms} = \sqrt{\frac{1}{T}{\int_{0}^{T}{{V(t)}^{2}{\mathbb{d}t}}}}$

Next, the value of the synthesized wave and the effective value duringthe APT drive are compared using this equation. First, the effectivevalue during the APT drive is calculated from a value of the COM1providing All-ON display. The equation is as follows:$\sqrt{\frac{{\left( {16.5\quad V} \right)^{2} \times 1} + {\left( {1.5\quad V} \right)^{2} \times 159}}{160}} = {2.0\quad V}$

Solving the equation gives an effective value of 2.0V.

Next, an effective value for the dummy common portion is calculatedusing the following equation:$\sqrt{\frac{{\left( {3\quad V} \right)^{2} \times 96} + {\left( {0\quad V} \right)^{2} \times 96}}{192}} = {2.1\quad V}$

Solving the equation gives an effective value of 2.1V which is somewhathigher than the effective value in the APT drive. Thus, the dummy commonwiring portions are constantly placed in the ON display state becausethey are applied with a little higher voltage than that for All-ONdisplay in the APT drive.

In a case where the SEG1 data indicates a display based on a 1-dotON/2-dot OFF pattern, an effective value for the dummy common wirings iscalculated based on the following equation:$\sqrt{\frac{{\left( {3\quad V} \right)^{2} \times 48} + {\left( {0\quad V} \right)^{2} \times 48}}{96}} = {2.1\quad V}$Solving the equation gives an effective value of 2.1V.

Thus, the effective value for the dummy common portion is greater than2.0V and hence, the dummy common portion can be placed in the whitedisplay state irrespective of the display data applied to the segment.

FIG. 3 is a block diagram showing an example of circuit blocks forgenerating the aforesaid dummy segment signal and dummy common signal. AVIDEO circuit 10 is a controller generating a variety of signals fordriving the liquid crystal display panel. The signal LP (line pulse) orFLM signal (frame pulse) outputted from the VIDEO circuit is inputted toa liquid-crystal AC-field generating circuit 11 which divides down theinput signal thereby generating the liquid-crystal AC-field generatingsignal (M signal). The dividing value is determined taking the displayquality of the liquid crystal panel into consideration and is normally aprime number. The M signal is committed to a level shift circuit 12 forshifting an amplitude level of the signal to that of the segment voltagefor APT drive. The level-shifted signal, as the dummy segment signal, issupplied to the dummy segment wirings of a liquid crystal panel 13. Thelevel-shifted signal is also divided down to ½ by a timing generatorcircuit 14 so that the resultant signal, as the dummy common signal, issupplied to the dummy common wirings of the liquid crystal panel 13.

In a case where the liquid crystal panel is a color display panel inwhich the dummy segment wiring portions are provided with color filtersR, B and G similarly to the arrangement of the display screen, threedummy segment wirings corresponding to the respective colors may be laidoutside of the display screen and may be applied with the aforesaiddummy segment signal whereby a white frame can be displayed outside thecolor display screen. The three lines may be shorted at place spacedaway from the display screen. The dummy segment wirings corresponding tothe tri-color filters may be unified into a single thick wire. On theother hand, a frame of a specific color can be displayed by applying theaforesaid dummy segment signal to any one of the three dummy segmentwirings while placing the other dummy segment wirings in the OFF state.The dummy common wirings are laid in a manner that a single line isextended in a similar way to the arrangement of the display screen andat respective places above and below the display screen. The dummycommon wirings are applied with the dummy common signal. Thus, theinvention is applicable to both the monochromatic and the color liquidcrystal display device of the passive drive system.

As described above, the liquid crystal display device according to theinvention is adapted to apply the waveform to the common electrodes tobe driven for the frame display, the waveform exceeding the selectionvoltage of any segment signal waveform for liquid crystal selection, andto apply the waveform to the segment electrodes to be driven for theframe display, the waveform exceeding the selection voltage of anycommon signal for liquid crystal selection. This permits the frame to bedisplayed without causing any interference with the conventional APTdrive (passive drive).

Furthermore, the waveform applied to the common electrodes to beconstantly placed in the ON state is generated based on the inputsignal-to the driver IC and the potential for driving the liquid crystalpanel. Hence, the invention can be readily implemented at low costwithout increasing the scale of the circuit.

The width of the frame can be readily adjusted by changing the number orwidth of an ITO wiring defining each dummy portion.

Thus is provided the easy and low-cost frame display outside the displayscreen of the passive drive system without being restricted by thespecification of the liquid crystal controller or the driver.Accordingly, the invention contributes to enhanced qualities of consumerproducts such as cameras, cellular phones and watches in the field ofelectronics where the liquid crystal display devices are widely used.

1-7. (canceled)
 8. A liquid crystal display device comprising; a liquidcrystal panel including a transparent plate formed with a group ofsegment electrodes, a transparent counter plate formed with a group ofcommon electrodes, and a liquid crystal layer interposed between thetransparent plate and the transparent counter plate; and a driver IC fordriving the liquid crystal panel, wherein a driving signal from thedriver IC is inputted to a segment electrode and a common electrodeconstituting a pixel to be driven for image display, whereas a waveformgenerated based on an input signal to the driver IC is inputted to acommon electrode to be placed in a normally ON state.
 9. A liquidcrystal display device comprising; a liquid crystal panel including atransparent plate formed with a group of segment electrodes, atransparent counter plate formed with a group of common electrodes, anda liquid crystal layer interposed between the transparent plate and thetransparent counter plate; and a driver IC for driving the liquidcrystal panel, wherein a driving signal from the driver IC is inputtedto a segment electrode and a common electrode constituting a pixel to bedriven for image display, whereas a common electrode to be placed in anormally ON state is applied with a waveform which is asynchronous to anFLM signal, has an equal H·L time in one period and does not coincidewith an M signal.
 10. A liquid crystal display device comprising: aliquid crystal panel comprised of a first transparent plate having aplurality of segment electrodes, a second transparent plate having aplurality of common electrodes and being spaced-apart from and oppositeto the first transparent plate to define a gap therebetween, and aliquid crystal layer disposed in the gap between the first and secondtransparent electrodes, the plurality of segment and common electrodescomprising a preselected number of segment and common electrodes forreceiving driving segment and common signals, respectively, and defininga plurality of pixels arranged in a matrix for displaying an image;wherein the plurality of segment electrodes comprises at least oneremaining segment electrode to be placed in a normally ON state and forreceiving a segment signal waveform so that an effective voltage valuebetween the segment signal waveform and any waveform of the drivingcommon signals exceeds a selection voltage applied across the liquidcrystal layer, and the plurality of common electrodes comprises at leastone remaining common electrode to be placed in a normally ON state andfor receiving a common signal waveform so that an effective voltagevalue between the common signal waveform and any waveform of the drivingsegment signals exceeds the selection voltage applied across the liquidcrystal layer, thereby displaying a frame on a portion of the liquidcrystal panel not corresponding to the pixels.
 11. A liquid crystaldisplay device according to claim 10; wherein a waveform obtained bysynthesis of the common signal waveform and the waveform of the drivingsegment signals has an effective voltage value greater than an effectivevoltage value of a waveform applied to an ON-state liquid crystal in thepixels.
 12. A liquid crystal display device according to claim 10;further comprising a driver integrated circuit for outputting at leastone of the driving segment signals and the driving common signals, andfor generating at least one of the common signal waveform and thesegment signal waveform in accordance with an input signal to the driverintegrated circuit.
 13. A liquid crystal display device according toclaim 12; wherein the common signal waveform is asynchronous to a frameline marker signal, has an equal H·L time in one period, and does notcoincide with a liquid-crystal AC-field generating signal.
 14. A liquidcrystal display device according to claim 13; wherein the common signalwaveform is a signal waveform obtained by dividing down theliquid-crystal AC-field generating signal for level shift to the samepotential as that of a segment voltage.
 15. A liquid crystal displaydevice according to claim 14; wherein the common signal waveform is asignal waveform obtained by dividing down the liquid-crystal AC-fieldgenerating signal to ½.
 16. A liquid crystal display device according toclaim 10; wherein the segment signal waveform has the same period as aliquid-crystal AC-field generating signal and the same potential as thecommon signal waveform.
 17. A liquid crystal display device comprising:a liquid crystal panel comprised of a liquid crystal material disposedbetween a plurality of segment and common electrodes defining aplurality of pixels arranged in a matrix; and a driver integratedcircuit for generating driving segment signals and driving commonsignals to drive preselected ones of the segment and common electrodes,respectively, to display an image on the liquid crystal panel, and forgenerating a segment signal waveform and a common signal waveform todrive one of the segment electrodes and one of the common electrodes,respectively, each placed in a normally ON state and not correspondingto the preselected ones of the segment and common electrodes,respectively, so that a frame is displayed at a portion of the liquidcrystal panel not corresponding to the pixels.
 18. A liquid crystaldisplay device according to claim 17; wherein an effective voltage valuebetween the segment signal waveform and any waveform of the drivingcommon signals exceeds a selection voltage applied across the liquidcrystal material.
 19. A liquid crystal display device according to claim18; wherein an effective voltage value between the common signalwaveform and any waveform of the driving segment signals exceeds aselection voltage applied across the liquid crystal material.
 20. Aliquid crystal display device according to claim 17; wherein aneffective voltage value between the common signal waveform and anywaveform of the driving segment signals exceeds a selection voltageapplied across the liquid crystal material.
 21. A liquid crystal displaydevice according to claim 17; wherein the common signal waveform isasynchronous to a frame line marker signal, has an equal H·L time in oneperiod, and does not coincide with a liquid-crystal AC-field generatingsignal.
 22. A liquid crystal display device according to claim 21;wherein the common signal waveform is a signal waveform obtained bydividing down the liquid-crystal AC-field generating signal for levelshift to the same potential as that of a segment voltage.
 23. A liquidcrystal display device according to claim 21; wherein the common signalwaveform is a signal waveform obtained by dividing down theliquid-crystal AC-field generating signal to ½.
 24. A liquid crystaldisplay device according to claim 17; wherein the segment signalwaveform has the same period as a liquid-crystal AC-field generatingsignal and the same potential as the common signal waveform.
 25. Aliquid crystal display device according to claim 17; wherein each of thesegment electrode and the common electrode not corresponding to thepreselected ones of the segment and common electrodes, respectively,comprises a dummy electrode disposed outside of segment and commonelectrodes, respectively, defining the pixels.
 26. A liquid crystaldisplay device according to claim 17; wherein segment electrode notcorresponding to the preselected ones of the segment electrodescomprises a dummy segment electrode disposed outside of the segmentelectrodes, respectively, defining the pixels.
 27. A liquid crystaldisplay device according to claim 17; wherein the common electrode notcorresponding to the preselected ones of the common electrodes comprisesa dummy common electrode disposed outside of the common electrodes,respectively, defining the pixels.